Limits of the Nuclear Ensemble Method for Electronic Spectra Simulations: Temperature Dependence of the (<i>E</i>)-Azobenzene Spectrum

Sršeň, Štěpán; Sita, Jaroslav; Slavı́ček, Petr; Ladányi, Vít; Heger, Dominik

doi:10.1021/acs.jctc.0c00579

Cited by 46 publications

(49 citation statements)

References 67 publications

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“… 12 , 32 Similar approaches have been proposed already in 1980s under the name of “reflection principle”. 33 , 34 The method has been successfully employed for a broad variety of molecular systems (e.g., refs ( 35 − 44 )), and an optimal sampling strategy from a statistical perspective has been discussed recently. 45 …”

Section: Introductionmentioning

confidence: 99%

Calculating Photoabsorption Cross-Sections for Atmospheric Volatile Organic Compounds

Prlj

Marsili

Hutton

et al. 2021

ACS Earth Space Chem.

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Characterizing the photochemical reactivity of transient volatile organic compounds (VOCs) in our atmosphere begins with a proper understanding of their abilities to absorb sunlight. Unfortunately, the photoabsorption cross-sections for a large number of transient VOCs remain unavailable experimentally due to their short lifetime or high reactivity. While structure–activity relationships (SARs) have been successfully employed to estimate the unknown photoabsorption cross-sections of VOCs, computational photochemistry offers another promising strategy to predict not only the vertical electronic transitions of a given molecule but also the width and shape of the bands forming its absorption spectrum. In this work, we focus on the use of the nuclear ensemble approach (NEA) to determine the photoabsorption cross-section of four exemplary VOCs, namely, acrolein, methylhydroperoxide, 2-hydroperoxy-propanal, and (microsolvated) pyruvic acid. More specifically, we analyze the influence that different strategies for sampling the ground-state nuclear density—Wigner sampling and ab initio molecular dynamics with a quantum thermostat—can have on the simulated absorption spectra. We highlight the potential shortcomings of using uncoupled harmonic modes within Wigner sampling of nuclear density to describe flexible or microsolvated VOCs and some limitations of SARs for multichromophoric VOCs. Our results suggest that the NEA could constitute a powerful tool for the atmospheric community to predict the photoabsorption cross-section for transient VOCs.

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Section: Introductionmentioning

confidence: 99%

Calculating Photoabsorption Cross-Sections for Atmospheric Volatile Organic Compounds

Prlj

Marsili

Hutton

et al. 2021

ACS Earth Space Chem.

Self Cite

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“…S139). Explaining this would require computational studies beyond single geometries, e.g., molecular dynamics simulations or Wigner distributions [58]. Judging the performance of the two used functionals by comparing with the experiment, we find that TD-ωB97X-D performs particularly well for the excitation energies of the first band (Fig.…”

Section: Spectral Propertiesmentioning

confidence: 90%

Towards low-energy-light-driven bistable photoswitches: ortho-fluoroaminoazobenzenes

Kuntze

Viljakka

Titov

et al. 2021

Photochem Photobiol Sci

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Thermally stable photoswitches that are driven with low-energy light are rare, yet crucial for extending the applicability of photoresponsive molecules and materials towards, e.g., living systems. Combined ortho-fluorination and -amination couples high visible light absorptivity of o-aminoazobenzenes with the extraordinary bistability of o-fluoroazobenzenes. Herein, we report a library of easily accessible o-aminofluoroazobenzenes and establish structure–property relationships regarding spectral qualities, visible light isomerization efficiency and thermal stability of the cis-isomer with respect to the degree of o-substitution and choice of amino substituent. We rationalize the experimental results with quantum chemical calculations, revealing the nature of low-lying excited states and providing insight into thermal isomerization. The synthesized azobenzenes absorb at up to 600 nm and their thermal cis-lifetimes range from milliseconds to months. The most unique example can be driven from trans to cis with any wavelength from UV up to 595 nm, while still exhibiting a thermal cis-lifetime of 81 days. Graphical abstract

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“…For further details on the source of this type of error and the characteristics, we refer to the work of Srsen et al. 46 …”

Section: Methodsmentioning

confidence: 99%

Multiconfigurational Quantum Chemistry Determinations of Absorption Cross Sections (σ) in the Gas Phase and Molar Extinction Coefficients (ε) in Aqueous Solution and Air–Water Interface

Borrego-Sánchez

Zemmouche

Carmona‐García

et al. 2021

J. Chem. Theory Comput.

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Theoretical determinations of absorption cross sections (σ) in the gas phase and molar extinction coefficients (ε) in condensed phases (water solution, interfaces or surfaces, protein or nucleic acids embeddings, etc.) are of interest when rates of photochemical processes, J = ∫ ϕ(λ) σ(λ) I (λ) dλ, are needed, where ϕ(λ) and I (λ) are the quantum yield of the process and the irradiance of the light source, respectively, as functions of the wavelength λ. Efficient computational strategies based on single-reference quantum-chemistry methods have been developed enabling determinations of line shapes or, in some cases, achieving rovibrational resolution. Developments are however lacking for strongly correlated problems, with many excited states, high-order excitations, and/or near degeneracies between states of the same and different spin multiplicities. In this work, we define and compare the performance of distinct computational strategies using multiconfigurational quantum chemistry, nuclear sampling of the chromophore (by means of molecular dynamics, ab initio molecular dynamics, or Wigner sampling), and conformational and statistical sampling of the environment (by means of molecular dynamics). A new mathematical approach revisiting previous absolute orientation algorithms is also developed to improve alignments of geometries. These approaches are benchmarked through the n π* band of acrolein not only in the gas phase and water solution but also in a gas-phase/water interface, a common situation for instance in atmospheric chemistry. Subsequently, the best strategy is used to compute the absorption band for the adduct formed upon addition of an OH radical to the C6 position of uracil and compared with the available experimental data. Overall, quantum Wigner sampling of the chromophore with molecular dynamics sampling of the environment with CASPT2 electronic-structure determinations arise as a powerful methodology to predict meaningful σ(λ) and ε(λ) band line shapes with accurate absolute intensities.

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Limits of the Nuclear Ensemble Method for Electronic Spectra Simulations: Temperature Dependence of the (E)-Azobenzene Spectrum

Cited by 46 publications

References 67 publications

Calculating Photoabsorption Cross-Sections for Atmospheric Volatile Organic Compounds

Calculating Photoabsorption Cross-Sections for Atmospheric Volatile Organic Compounds

Towards low-energy-light-driven bistable photoswitches: ortho-fluoroaminoazobenzenes

Multiconfigurational Quantum Chemistry Determinations of Absorption Cross Sections (σ) in the Gas Phase and Molar Extinction Coefficients (ε) in Aqueous Solution and Air–Water Interface

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